The popularity of peer-to-peer (P2P) networks has grown significantly due to ever-increasing demand for digital content, such as data file, movies, music, videogames and software applications. P2P networks allow peer client computers to share content with each other directly rather than through a central server. BitComet® and μTorrent™ are examples of popular P2P networking applications. P2P networks usually use BitTorrent® protocol or other type of peering protocol for communication. These protocols allow a peer client computer to send/receive requests for data objects, such as files, to/from other peer client computers in the same P2P network. The requestor peer client computer then downloads the requested data objects in pieces from multiple source peer client computers and reassembles the data object. This architecture of the P2P networks provides enhanced scalability and service robustness.
However, unregulated nature of P2P networks and the ever-growing number of the users makes these networks very vulnerable to the spread of malware, such as viruses, worms, Trojans, spyware, etc. The malware may be planted into file archives containing necessary network information or inserted into popular data objects, such as free software applications, which are shared among peer client computers. Since not all peer client computers have antivirus applications and those that do may not be updated with the latest antivirus definitions, the P2P network is extremely vulnerable to spread of malware. Accordingly, there is an urgent need to detect and prevent spread of malware in the P2P networks.